Compact, High-Efficiency, Dual-Output
Step-Up and LCD Bias DC-DC Converter
MAX1677
Typical Operating Characteristics (continued)
(Circuits of Figures 2 and 3, T
A
= +25°C, unless otherwise noted.)
MAIN BOOST CONVERTER SWITCHING
WAVEFORMS (PWM MODE)
MAX1677-10
MAIN BOOST CONVERTER SWITCHING
WAVEFORMS (PFM MODE)
MAX1677-11
2V/
div
100mA/
div
V
LX
2V/
div
V
LX
I
LX
100mA/
div
I
LX
50mV/
div
1µs/div
2.4V
IN
, 3.3V
OUT
,
200mA I
OUT
V
RIPPLE
20mV/
div
V
RIPPLE
2µs/div
1.2V
IN
, 3.3V
OUT
,
20mA I
OUT
MAIN BOOST CONVERTER SWITCHING
WAVEFORMS (PFM MODE, 50mA OUTPUT)
MAX1677-12
LCD SWITCHING WAVEFORMS
MAX1677-13
2V/
div
V
LX
10mV/
div
V
LX
100mA/
div
I
LX
200mA/
div
100mV/
div
I
LX
V
RIPPLE
50mV/
div
10µs/div
PFM, 1.2V
IN
,
3.3V
OUT
, 50mA I
OUT
V
RIPPLE
5µs/div
LDCLX CURRENT LIMIT = 350mA,
2.4V
IN,
+12V
OUT,
10mA LOAD
LCD SWITCHING WAVEFORMS
(50kΩ FROM LCDPOL TO OUT)
MAX1677-14
MAIN BOOST CONVERTER
LOAD TRANSIENT
MAX1677-15
10mV/
div
V
LX
50mV/
div
V
RIPPLE
200mA/
div
100mV/
div
I
LX
200mA/
div
V
RIPPLE
I
OUT
2µs/div
LCDLX CURRENT LIMIT = 225mA,
2.4V
IN,
+12V
OUT,
10mA LOAD
2ms/div
V
IN
= 2.4V, V
OUT
= 3.3V
I
LOAD
= 0 to 200mA
6
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MAXIM [ MAXIM INTEGRATED PRODUCTS ]
